Indian Institute of Technology, IIT Bombay

The IIT-B cutoff for B.Tech courses are varying according to specializations. The cutoff ranks of CSE goes very high. The last year cutoff ranks of some specializations are given below for an idea.
1. CSE (Closing rank 21)
2. Civil (Closing rank 661)
3. Electrical (Closing rank 100)
4. Aerospace (Closing rank 564)
5. Chemical (Closing rank 604)
6. Mechanical (Closing rank 250)
So from above you have to score at least 220 marks in JEE Advanced for getting admission here in Civil engineering branch.

For IIT BOMBAY you have to secure the top rank in the JEE ADVANCE exam.
From JEE MAINS you get the NIT's college not IIT'S.
I am sending you an authentic link from where you get all information of cutoffs for IIT BOMBAY.please check it out.
link-https://www.shiksha.com/university/iit-bombay-indian-institute-of-technology-mumbai-54212/cutoff

Yes, you can pursue this course if you fulfill the following eligibility.Eligibility: The candidate must have passed 10+2 or equivalent examination by a recognized board and B.Sc physics with 50% or above marks in aggregate. The candidate must have passed B.Sc. (General/Programme/B.Sc).